Multiscale Modeling of Fluid Turbulence and Flocculation in Industrial Applications

The present effort is the development of a multiscale modeling, simulation methodology for investigating complex phenomena arising from flowing fiber suspensions. Here, a mathematically rigorous, multiscale modeling methodology is presented capable of coupling behaviors from the Kolmogrov turbulence scale through the full scale system in which a fiber suspension is flowing, (i) a computational simulation framework built around this methodology into which techniques for investigating behaviors at the various scales can be effectively integrated, and (ii) a proof of concept of the developed core technologies using synergetic interactions with experimental studies. Here the key aspect is adaptive hierarchical modeling. Numerical results are presented for which focus is on fiber floc formation and destruction by hydrodynamic forces in turbulent flows. Specific consideration was given to moleculardynamic-type simulations of viscoelastic fibers in which the fluid flow is predicted by a method which is a hybrid between Direct Numerical Simulations (DNS) and Large Eddy Simulation techniques (LES) and fluid fibrous structure interactions (FSI) will be taken into account. The present results may elucidate the physics behind the break up of a fiber floc, opening the possibility for developing a meaningful numerical model of the fiber flow at the continuum level where an Eulerian multi-phase flow model can be developed for industrial use.